The present invention relates to apparatus for heating a fluid and more particularly to apparatus for quickly and controllably heating flows of fluids such as blood plasma which may be needed for infusion into a hemorrhaging patient.
A major cause of death in military combat is rapid hemorrhage. To treat hemorrhaging, it is often necessary to quickly infuse a substantial volume of fluid, e.g. whole blood, plasma or blood substitute, so as to maintain an adequate blood volume and circulation. However, to preserve them, such materials are typically refrigerated and it is necessary to warm them before infusion so as to avoid shock to the patient's system. While it is desired to heat the infusate quickly, the temperatures of surfaces in contact with the infusate should not exceed 40-42 degrees C. since, at higher temperatures, protein denaturation and red cell damage can occur. It is also important that any electrical power or potentials utilized in the heating process be effectively isolated from the patient.
Most prior art blood heaters utilize a relatively large water bath reservoir which is preheated to 39-40 degrees C. The water is pumped rapidly through a heat exchanger through which the infusate is perfused, the two fluids typically being separated by a thin, usually metallic, heat exchange surface. These prior art devices are relatively large and cumbersome due to the need for the water bath and water pump as well as the heat exchanger and associated conduits. Such devices accordingly have not been suitable for use in the field either in combat or emergency situations.
Among the objects of the present invention may be noted the provision of novel fluid heating apparatus; the provision of such apparatus which is highly compact; the provision of such apparatus which is easily transportable and which can be operated from battery power; the provision of such apparatus which is highly efficient; the provision of such apparatus which does not require a water bath reservoir; the provision of such apparatus which does not require a substantial warmup period; the provision of such apparatus which provides accurate temperature control; the provision of intrinsic electrical insulation between the heat exchanging element and the power source; the provision of a heat exchanger which is easily removed for replacement without making or breaking electrical power connections; the provision of such apparatus which does not waste substantial quantities of the fluid being heated; the provision of such apparatus which is highly reliable and which is of relatively simple and inexpensive construction. Other objects and features will be in part apparent and in part pointed out hereinafter.